Methods and systems for light source diagnostics

ABSTRACT

A method for use in testing an operational status of a light source for illuminating a scene, comprises using a camera to capture a first image when the light source is disabled, the light source having a fixed spatial relationship relative to the camera, and using the camera to capture a second image when the light source is enabled. The method comprises determining a test result indicating the operational status of the light source based at least in part on a light source setting when the camera captures each of the first and second images, the light source setting indicating whether the light source is disabled or enabled when the camera captures the first and second images and at least one of: one or more camera settings when the camera captures the first and second images, and one or more image properties of the first and second images. Such a method may be used for testing the operational status of a light source and, in particular, though not exclusively, for use in automatically testing the operational status of a camera flash of a mobile electronic device.

FIELD

The present disclosure relates to a method, a system, a diagnosticsapplication, and a device such as a mobile electronic device for use intesting the operational status of a light source and, in particular,though not exclusively, for use in automatically testing the operationalstatus of a camera flash of a mobile electronic device.

BACKGROUND

It is known to perform a manual diagnostic test or check of a cameraflash of a mobile electronic device in which a user or operator of themobile electronic device needs to provide feedback indicating whether ornot the camera flash of the mobile electronic device actually operateswhen enabled. However, such manual diagnostic tests or checks aretime-consuming and are susceptible to human error or fraud.

SUMMARY

According to an aspect of the present disclosure there is provided amethod for use in testing an operational status of a light source forilluminating a scene, the light source having a fixed spatialrelationship relative to a camera, and the method comprising:

-   -   using the camera to capture a first image when the light source        is disabled;    -   using the camera to capture a second image when the light source        is enabled; and    -   determining a test result indicating the operational status of        the light source based at least in part on:    -   a light source setting when the camera captures each of the        first and second images, the light source setting indicating        whether the light source is disabled or enabled when the camera        captures the first and second images; and    -   at least one of:        -   one or more camera settings when the camera captures the            first and second images; and        -   one or more image properties of the first and second images.

Such a method may be used for testing the operational status of a lightsource and, in particular, though not exclusively, for use inautomatically testing the operational status of a camera flash of amobile electronic device.

The one or more camera settings may comprise an ISO setting of an imagesensor of the camera, an exposure index of an image sensor of thecamera, a sensitivity setting of an image sensor of the camera, or again setting of an image sensor of the camera.

The one or more camera settings may comprise a shutter speed or anexposure time of the camera.

The one or more camera settings may comprise an aperture setting, anf-stop, or an f-number of the camera.

The one or more image properties may comprise an image brightnessparameter.

The image brightness parameter may comprise an average brightness of animage or an average intensity of an image, or an average brightness oran average intensity of a pre-defined portion or a pre-defined area ofan image.

The one or more image properties may comprise an image file size.

The method may comprise reading the first and second images from thecamera.

The method may comprise determining, for each of the first and secondimages, the light source settings, the one or more camera settings, andthe one or more image properties.

The method may comprise extracting from metadata associated or storedwith each of the first and second images, the light source settings, theone or more camera settings, and the one or more image properties foreach of the first and second images.

The method may comprise reading the light source settings, the one ormore camera settings, and the one or more image properties for the firstand second images from the camera.

The method may comprise determining the image properties of the firstand second images from image data of the first and second images.

The method may comprise determining whether the first and second imagesare images of the same scene.

The method may comprise:

-   -   determining, for each of the one or more camera settings,        whether a camera setting difference between a camera setting        value associated with the first image and a camera setting value        associated with the second image complies with a corresponding        predetermined camera setting criterion; and    -   determining, for each of the one or more image properties,        whether an image property difference between an image property        value associated with the first image and an image property        value associated with the second image complies with a        corresponding predetermined image property criterion.

The method may comprise selecting each predetermined camera settingcriterion and each predetermined image property criterion based at leastin part on the corresponding camera setting value and/or thecorresponding image property value when the camera captures the firstimage. This may be advantageous where the first image captures a scenewhich is relatively bright.

The method may comprise determining a positive test result indicatingthat the light source is operational, or that the light source operatescorrectly or in compliance with a predetermined performancespecification if:

-   -   the first and second images are determined to be images of the        same scene;    -   one or more of the camera setting differences comply with the        corresponding predetermined criterion; and    -   one or more of the image property differences comply with the        corresponding predetermined criterion.

The method may comprise determining a negative test result indicatingthat the light source is non-operational, or that the light source isfaulty or fails to comply with a predetermined performance specificationif:

-   -   the first and second images are determined to be images of the        same scene; and at least one of:    -   one or more of the camera setting differences fails to comply        with the corresponding predetermined criterion; and    -   one or more of the image property differences fails to comply        with the corresponding predetermined criterion.

The method may comprise determining a positive test result indicatingthat the light source is operational, or that the light source operatescorrectly or in compliance with a predetermined performancespecification if:

-   -   the first and second images are determined to be images of the        same scene;    -   the second image has a localised feature or artefact of a        greater brightness than one or more adjacent areas or regions of        the second image; and    -   the first image has no localised feature or artefact of a        greater brightness than one or more adjacent areas or regions of        the first image, which localised feature or artefact of the        first image is located at a position in the first image that        corresponds to a position of the localised feature or artefact        in the second image.

The method may comprise determining a negative test result indicatingthat the light source is non-operational, or that the light source isfaulty or fails to comply with a predetermined performance specificationif:

-   -   it is determined that the first and second images are images of        the same scene;    -   the second image has a localised feature or artefact of a        greater brightness than one or more adjacent areas or regions of        the second image; and    -   the first image has a localised feature or artefact of a greater        brightness than one or more adjacent areas or regions of the        first image, which localised feature or artefact of the first        image is located at a position in the first image that        corresponds to a position of the localised feature or artefact        in the second image.

The method may comprise using an image processing algorithm such as amachine learning algorithm to identify any localised feature or artefactof a greater brightness than one or more adjacent areas or regions ofthe first and/or second images.

The method may comprise determining an inconclusive test result for theoperational status of the light source if it is determined that thefirst and second images are not images of the same scene.

Determining whether the first and second images are images of the samescene may comprise:

-   -   comparing the first and second images; and    -   determining whether the first and second images correspond to        images of the same scene based on the results of the comparison        of the first and second images.

Determining whether the first and second images are images of the samescene may comprise:

-   -   identifying an object in the first image; and    -   identifying the same object in the second image.

Determining whether the first and second images are images of the samescene may comprise using an image processing algorithm to identify theobject in the first image and to identify the same object in the secondimage. The image processing algorithm may be based on a machine learningalgorithm.

Determining whether the first and second images are images of the samescene may comprise:

-   -   determining, for each of one or more properties of the object, a        first value for the property of the object from the first image        and a second value for the property of the object from the        second image; and    -   determining that the first and second images are images of the        same scene if, for each of the one or more properties of the        object, the first and second values for the property of the        object comply with a corresponding predetermined criterion.

Determining whether the first and second images are images of the samescene may comprise:

-   -   determining, for each of the one or more properties of the        object, a difference between the determined first and second        values for the property of the object; and    -   determining that the first and second images are images of the        same scene if, for each of the one or more properties of the        object, the determined difference between the determined first        and second values for the property of the object is less than a        corresponding predetermined threshold value.

The one or more properties of the object may comprise one or more of: asize of the object, an aspect ratio of the object, a position of theobject and an orientation of the object.

Determining whether the first and second images are images of the samescene may comprise:

-   -   determining a quantitative degree of similarity between the        first and second images; and    -   determining that the first and second images are images of the        same scene if the quantitative degree of similarity between the        first and second images complies with a predetermined image        similarity criterion.

Determining whether the first and second images are images of the samescene may comprise determining that the first and second images areimages of the same scene if a difference between the quantitative degreeof similarity between the first and second images is less than apredetermined threshold value.

The quantitative degree of similarity between the first and secondimages may comprise a cross-correlation between the first and secondimages or a cross-correlation between corresponding portions of thefirst and second images.

Determining whether the first and second images are images of the samescene may comprise:

-   -   determining a distance from the camera to an object located at a        predetermined position in the first image;    -   determining a distance from the camera to an object located at a        predetermined position in the second image, which predetermined        position in the second image corresponds to the predetermined        position in the first image; and    -   determining that the first and second images are images of the        same scene if the determined distance from the camera to the        object at the predetermined position in the first image and the        determined distance from the camera to the object at the        predetermined position in the second image comply with a        predetermined distance criterion.

Determining whether the first and second images are images of the samescene may comprise determining that the first and second images areimages of the same scene if a difference between the determined distancefrom the camera to the object at the predetermined position in the firstimage and the determined distance from the camera to the object at thepredetermined position in the second image is less than a predeterminedthreshold value.

Determining whether the first and second images are images of the samescene may comprise:

-   -   measuring a distance from the camera to the object at the time        of capture of the first image; and    -   measuring a distance from the camera to the object at the time        of capture of the second image.

Measuring the distance from the camera to the object at the time ofcapture of each of the first and second images may comprise executing anaugmented reality (AR) application on a computing device. Such anapplication may comprise a third-party AR library, such as ARCore, whichprovides an application programming interface (API) to the ARapplication. The computing device may be configured for communicationwith the camera. Further, the camera may form part of, be defined by, orbe fixed or attached to, the computing device.

Measuring the distance from the camera to the object at the time ofcapture of each of the first and second images may comprise:

-   -   transmitting modulated electromagnetic radiation from an emitter        to the object and receiving modulated electromagnetic radiation        reflected from the object at a detector; and    -   determining a delay between emitting the modulated        electromagnetic radiation from the emitter and detecting the        reflected modulated electromagnetic radiation at the receiver,    -   wherein the emitter and the detector have a fixed spatial        relationship with respect to each other.

The emitter and the detector may have a fixed spatial relationship withrespect to the camera. The emitter and the detector may be fixed orattached to the camera. The modulated electromagnetic radiation maycomprise amplitude modulated electromagnetic radiation.

The modulated electromagnetic radiation may comprise a stream of pulsesof electromagnetic radiation.

The modulated electromagnetic radiation may comprise frequency modulatedelectromagnetic radiation.

The electromagnetic radiation may comprise light, for example visible orinfrared (IR) light.

The emitter may comprise a light emitter.

The light emitter may comprise a light emitting diode (LED). The lightemitter may comprise a source of coherent light such as a laser, forexample a laser diode.

The emitter may comprise one or more LEDs.

The emitter may comprise one or more laser diodes.

The detector may comprise an optical detector such as a photodiode.

The detector may comprise a time of flight (ToF) camera.

Determining whether the first and second images are images of the samescene may comprise:

-   -   measuring any movements of the camera between a time of capture        of the first image and a time of capture of the second image;        and    -   determining that the first and second images are images of the        same scene if the size of any movements of the camera comply        with one or more predetermined movement criteria.

Determining whether the first and second images are images of the samescene may comprise determining that the first and second images areimages of the same scene if the size of any movements of the camera areless than one or more predetermined threshold values.

Determining whether the first and second images are images of the samescene may comprise:

-   -   determining a location and orientation of the camera at the time        of capture of each of the first and second images; and    -   determining that the first and second images are images of the        same scene if the determined locations of the camera at the        times of capture of the first and second images comply with a        predetermined location criterion and the determined orientations        of the camera at the times of capture of the first and second        images comply with a corresponding predetermined orientation        criterion.

Determining whether the first and second images are images of the samescene may comprise determining that the first and second images areimages of the same scene if a difference between the determinedlocations of the camera at the times of capture of the first and secondimages are less than a corresponding predetermined location thresholdvalue and a difference between the determined orientations of the cameraat the times of capture of the first and second images are less than acorresponding predetermined orientation threshold value.

The light source may comprise a camera flash provided with, housed with,or fixed or attached to, the camera.

The camera and the light source may form part of, be defined by, or befixed or attached to, a device such as a computing device.

The computing device may be a mobile electronic device comprising amobile phone, a smart phone, a cell phone, or a tablet, for example. Thecomputing device may be a desktop computer, a laptop computer, or aworkstation. The computing device may be an Internet-of-Things (IoT)device such as a smart home appliance or a smart security device.

The camera and the light source may form part of, be defined by, or befixed or attached to, a security system for a building, a fixedstructure, or an enclosed area or space.

The camera and the light source may form part of, be defined by, or befixed or attached to, a vehicle.

The light source may comprise, or be defined by, a light source providedwith the vehicle such as a head light or a tail light of the vehicle.

According to an aspect of the present disclosure there is provided anapplication for a mobile electronic device comprising a camera and alight source, or for a server configured for communication with a mobileelectronic device comprising a camera and a light source, wherein, whenexecuted by a processor of the mobile electronic device or a processorof the server, the application causes the mobile electronic device toperform any of the methods described above.

According to an aspect of the present disclosure there is provided amobile electronic device comprising the application as described above.

According to an aspect of the present disclosure there is provided aserver comprising the application as described above.

It should be understood that any one or more of the features of any oneof the foregoing aspects of the present disclosure may be combined withany one or more of the features of any of the other foregoing aspects ofthe present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

Various apparatus and methods for use in testing the operational statusof a light source will now be described by way of non-limiting exampleonly with reference to the following drawings of which:

FIG. 1 is a schematic of a mobile electronic device and a system for usein automatically testing the operational status of a camera flash of themobile electronic device;

FIG. 2 is a flow chart illustrating the initial steps of a method forautomatically testing the operational status of the camera flash of themobile electronic device shown in FIG. 1 ;

FIG. 3 shows a first image captured when the camera flash of the mobileelectronic device shown in FIG. 1 is disabled together with someassociated camera setting values and image property values and a secondimage captured when the camera flash of the mobile electronic deviceshown in FIG. 1 is enabled together with some associated camera settingvalues and image property values;

FIG. 4 is a flow chart illustrating a step of the method forautomatically testing the operational status of the camera flash of themobile electronic device, the step comprising determining whether thefirst and second images are images of the same scene;

FIG. 5 is a flow chart illustrating the final steps of the method forautomatically testing the operational status of the camera flash of themobile electronic device shown in FIG. 1 ;

FIG. 6 is a flow chart illustrating some alternative final steps of themethod for automatically testing the operational status of the cameraflash of the mobile electronic device shown in FIG. 1 ; and

FIG. 7 is a flow chart illustrating an alternative method fordetermining whether the first and second images are images of the samescene.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring initially to FIG. 1 there is shown a system, generallydesignated 1, for use in automatically testing the operational status ofa camera flash of the mobile electronic device 2. The mobile electronicdevice 2 includes a memory 4, a processor 6, a communication interface7, a user interface in the form of a touchscreen 8, a camera 10, a lightsource in the form of a camera flash 12, an infrared (IR) source in theform of an infrared light emitting diode (LED) 14, a photodiode 16 whichis configured for detection of infrared light emitted by the LED 14 andreflected back onto the photodiode 16, a motion sensor in the form of anaccelerometer 17 and an antenna 18. The memory 4 stores a diagnosticsapplication 19.

The system 1 includes a server which is generally designated 22 andwhich is located remotely from the mobile electronic device 2. Theserver 22 includes a memory 24, a processor 26, a communicationinterface 27, and a user interface 28. The memory 24 stores a computerprogram in the form of a diagnostics application 30, data 32 relating toone or more images captured by the mobile electronic device 2, anddiagnostic information 34 relating to the operational status of thecamera flash 12 of the mobile electronic device 2.

As shown in FIG. 1 , the mobile electronic device 2 and the server 22are configured for communication over the cloud 50 via the communicationinterface 7 and antenna 18 of the mobile electronic device 2 and thecommunication interface 27 of the server 22.

When executed by the processor 6 of the mobile electronic device 2, thediagnostics application 19 causes the mobile electronic device 2 toperform a method for automatically testing the operational status of thecamera flash 12 of the mobile electronic device 2.

As illustrated in FIG. 2 , the method 100 begins at step 101 with themobile electronic device 2 disabling the camera flash 12 and prompting auser of the mobile electronic device 2, via the user interface 8, to usethe camera 10 to capture a first image 60 of a scene. The methodcontinues at step 102 with the mobile electronic device 2 enabling thecamera flash 12 and prompting the user, via the user interface 8, to usethe camera 10 to capture a second image 62 of the same scene.

As will be described in more detail below, the processor 6 of the mobileelectronic device 2 then determines a test result indicating theoperational status of the camera flash 12 based at least in part on alight source setting indicating that the camera flash 12 is disabledwhen the camera 10 captures the first image, a light source settingindicating that the light source is enabled when the camera captures thesecond image, one or more camera settings when the camera 10 capturesthe first and second images, and one or more image properties of thefirst and second images.

Specifically, at step 104, the processor 6 of the mobile electronicdevice 2 extracts from metadata provided with the image data of thefirst and second images: the light source settings associated with thefirst and second images; the camera settings when the camera 10 capturesthe first and second images; and the one or more image properties of thefirst and second images. Specifically, the processor 6 of the mobileelectronic device 2 extracts or accesses the metadata provided with theimage data of the first and second images programmatically via anapplication programming interface (API) for the camera 10.

As illustrated in FIG. 3 , the camera settings include an ISO settingand a shutter speed or an exposure time used by the camera when thecamera 10 captures the first and second images 60, 62, and the imageproperties include image brightness parameter values associated with thefirst and second images 60, 62 and image file sizes of the first andsecond images 60, 62. The one or more brightness parameter values ofeach of the first and second images 60, 62 may, for example, comprise anaverage brightness or an average intensity of each of the first andsecond images 60, 62 or an average brightness or an average intensity ofa pre-defined portion or a pre-defined area of each of the first andsecond images 60, 62.

The method continues at step 106 of FIG. 2 with the processor 6 of themobile electronic device 2 then determining whether the first and secondimages are images of the same scene. Specifically, the processor 6 ofthe mobile electronic device 2 compares the first and second images 60,62 and determines whether the first and second images correspond toimages of the same scene based on the results of the comparison of thefirst and second images. More specifically and, with reference to FIG. 4, the processor 6 of the mobile electronic device 2 determines adistance from the camera 10 to an object 64 located at a predeterminedposition in the first image 60 and the processor 6 determines a distancefrom the camera 10 to the object 64 located at a predetermined positionin the second image 62, which predetermined position in the second image62 corresponds to the predetermined position in the first image 60. Theprocessor 6 then determines that the first and second images 60, 62 areimages of the same scene if the determined distance from the camera 10to the object 64 at the predetermined position in the first image 60 andthe determined distance from the camera 10 to the object 64 at thepredetermined position in the second image 62 comply with apredetermined distance criterion. For example, the processor 6determines that the first and second images 60, 62 are images of thesame scene if a difference between the determined distance from thecamera 10 to the object 64 at the predetermined position in the firstimage 60 and the determined distance from the camera 10 to the object 64at the predetermined position in the second image 62 is less than apredetermined threshold value. The processor 6 causes the camera 10 tomeasure the distance from the camera 10 to the object 64 at the time ofcapture of the first image 60 and to measure the distance from thecamera 10 to the object 64 at the time of capture of the second image62. More specifically, the processor 6 causes the LED 14 to transmitmodulated infrared light to the object 64 and the processor 6 causes thephotodiode 16 to detect a portion of the transmitted modulated infraredlight that is reflected from the object 64. The processor 6 thendetermines the distance from the camera 10 from the delay betweentransmitting the modulated infrared light from the LED 14 and detectingthe reflected modulated infrared light at the photodiode 16. One ofordinary skill in the art will understand that a variety of distancemeasurement techniques are possible using modulated infrared light.

For example, the modulated infrared light may be amplitude modulated andthe distance from the camera 10 to the object 64 may be determined fromthe delay between transmitting an amplitude modulated feature of theamplitude modulated infrared light from the LED 14 and the arrival ofthe same amplitude modulated feature of amplitude modulated infraredlight at the photodiode 16. The amplitude modulated infrared light may,for example, comprise a stream of pulses of infrared light and thedistance from the camera 10 to the object 64 may be determined from thedelay between transmitting a pulse of infrared light from the LED 14 andthe arrival of the same pulse of infrared light at the photodiode 16.Alternatively, the modulated infrared light may be frequency modulatedand the distance from the camera 10 to the object 64 may be determinedfrom a delay determined from a difference between a frequency of thefrequency modulated infrared light transmitted from the LED 14 and afrequency of the frequency modulated infrared light arriving at thephotodiode 16. Additionally or alternatively, the processor 6 causes anaugmented reality (AR) application to measure the distance from thecamera 10 to the object 64 at the time of capture of the first image 60and to measure the distance from the camera 10 to the object 64 at thetime of capture of the second image 62. More specifically, the processor6 executes an AR application causing the camera to first quantify thedimensional space between the camera 10 and the object 64 and then tomeasure the distance from the camera 10 to the object 64. Such anapplication may comprise a third-party AR library, such as ARCore, whichprovides an application programming interface (API) to the ARapplication.

Referring now to FIG. 5 , the method continues at step 108 with theprocessor 6 determining, for each of the one or more camera settings,whether a camera setting difference between a camera setting valueassociated with the first image 60 and a camera setting value associatedwith the second image 62 complies with a corresponding predeterminedcamera setting criterion. Similarly, at step 110, the processor 6determines, for each of the one or more image properties, whether animage property difference between an image property value associatedwith the first image 60 and an image property value associated with thesecond image 62 complies with a corresponding predetermined imageproperty criterion.

At step 112, the processor 6 determines whether one or more of thecamera setting differences comply with the corresponding predeterminedcriterion and whether one or more of the image property differencescomply with the corresponding predetermined criterion.

If the processor 6 determines that one or more of the camera settingdifferences comply with the corresponding predetermined criterion andthat one or more of the image property differences comply with thecorresponding predetermined criterion, at step 114 the processor 6determines a positive test result indicating that the light source isoperational, or that the light source operates correctly or incompliance with a predetermined performance specification and returnsthe positive test result to a user of the mobile electronic device 2 viathe user interface 8 and/or returns the positive test result to theserver 22 via the communication interfaces 7, 27 and the cloud 50 forstorage as the diagnostic information 34 in the memory 24 of the server22.

If the processor 6 determines that one or more of the camera settingdifferences fails to comply with the corresponding predeterminedcriterion or that one or more of the image property differences fails tocomply with the corresponding predetermined criterion, at step 116 theprocessor 6 determines a negative test result indicating that the lightsource is non-operational, or that the light source is faulty or failsto comply with a predetermined performance specification and returns thenegative test result to a user of the mobile electronic device 2 via theuser interface 8 and/or returns the negative test result to the server22 via the communication interfaces 7, 27 and the cloud 50 for storageas the diagnostic information 34 in the memory 24 of the server 22.

If at step 106 c, the processor 6 determines the determined distancesfrom the camera 10 to the object 64 at the predetermined position in thefirst and second images 60, 62 do not comply with the correspondingpredetermined criterion, the processor 6 determines that the first andsecond images 60, 62 are images of different scenes at step 106 e. Atstep 118, the processor 6 then determines that the test result isinconclusive and returns the inconclusive test result to a user of themobile electronic device 2 via the user interface 8 and/or returns theinconclusive test result to the server 22 via the communicationinterfaces 7, 27 and the cloud 50 for storage as the diagnosticinformation 34 in the memory 24 of the server 22.

In one specific example of the method for automatically testing theoperational status of the camera flash 12 of the mobile electronicdevice 2 described with reference to FIGS. 2-5 , the one or more camerasettings extracted from the metadata of the first and second images 60,62 may comprise an ISO setting of the camera 10 and a shutter speedsetting of the camera 10, the one or more image properties extractedfrom the metadata of the first and second images 60, 62 may comprise abrightness parameter and an image file size, and experiments withseveral different makes and models of smartphone have demonstrated thatthe camera flash 12 can be considered to be operational if at least twoof the following predetermined criteria are satisfied:

-   -   (i) the ISO setting value when the camera 10 captures the first        image 60 is less than the ISO setting value when the camera 10        captures the second image 62;    -   (ii) the shutter speed setting value when the camera 10 captures        the first image 60 is less than the shutter speed setting value        when the camera 10 captures the second image 62;    -   (iii) the image brightness parameter value when the camera 10        captures the first image 60 is greater than the image brightness        parameter value when the camera 10 captures the second image 62;        and    -   (iv) the image file size value when the camera 10 captures the        first image 60 is greater than the image file size value when        the camera 10 captures the second image 62.

Conversely, the camera flash 12 can be considered to be non-operationalif one or none of the predetermined criteria (i)-(iv) above aresatisfied.

In a variant of the method for automatically testing the operationalstatus of the camera flash 12 of the mobile electronic device 2described with reference to FIGS. 2-5 , the steps 108, 110, 112, 114,116 and 118 illustrated in FIG. 5 may be replaced with the steps 208,210, 214, 216 and 218 illustrated in FIG. 6 . Specifically, at step 208,the processor 6 determines whether the second image 62 has a localisedfeature or artefact of a greater brightness than one or more adjacentareas or regions of the second image 62. Such a localised feature orartefact of greater brightness than the one or more adjacent areas orregions of the second image 62 may arise as a result of a reflectionsuch as a specular reflection of the camera flash 12 from an object inthe scene.

If the processor 6 determines that the second image 62 has a localisedfeature or artefact of a greater brightness than one or more adjacentareas or regions of the second image 62 at step 208, the methodcontinues at step 210 with the processor 6 determining whether the firstimage 60 has a localised feature or artefact of a greater brightnessthan one or more adjacent areas or regions of the first image 60, whichlocalised feature or artefact of the first image 60 is located at aposition in the first image 60 that corresponds to a position of thelocalised feature or artefact in the second image 62.

If the processor 6 determines that the first image 60 has a localisedfeature or artefact of a greater brightness than one or more adjacentareas or regions of the first image 60, which localised feature orartefact of the first image 60 is located at a position in the firstimage 60 that corresponds to a position of the localised feature orartefact in the second image 62 at step 210, the method returns anegative test result at step 216 indicating that the camera flash 12 isnon-operational.

If the processor 6 determines that the first image 60 does not have alocalised feature or artefact of a greater brightness than one or moreadjacent areas or regions of the first image 60, which localised featureor artefact of the first image 60 is located at a position in the firstimage 60 that corresponds to a position of the localised feature orartefact in the second image 62 at step 210, the method returns apositive test result at step 214 indicating that the camera flash 12 isoperational.

If the processor 6 determines that the second image 62 does not have alocalised feature or artefact of a greater brightness than one or moreadjacent areas or regions of the second image 62, the method returns aninconclusive test result at step 218. Similarly, if at step 106 c, theprocessor 6 determines for each of the one or more properties of theobject 64, that the determined first and second values for the propertyof the object 64 do not comply with the corresponding predeterminedcriterion, the processor 6 determines that the first and second images60, 62 are images of different scenes at step 106 e and the processor 6determines an inconclusive test result at step 218.

In a first alternative to the method for determining whether the firstand second images are images of the same scene of steps 106 a-106 eillustrated in FIG. 4 , the processor 6 determines a quantitative degreeof similarity between the first and second images 60, 62, and theprocessor 6 determines that the first and second images 60, 62 areimages of the same scene if the quantitative degree of similaritybetween the first and second images 60, 62 comply with a predeterminedimage similarity criterion. For example, the processor 6 determines thatthe first and second images are images of the same scene if a differencebetween the quantitative degree of similarity between the first andsecond images is less than a predetermined threshold value. Morespecifically, the processor 6 determines a cross-correlation between thefirst and second images 60, 62 or a cross-correlation betweencorresponding portions of the first and second images 60, 62, and theprocessor 6 determines that the first and second images 60, 62 areimages of the same scene if the cross-correlation between the first andsecond images 60, 62 complies with a predetermined cross-correlationcriterion. For example, the processor 6 determines that the first andsecond images are images of the same scene if a difference between thecross-correlation between the first and second images is less than apredetermined threshold value.

In a second alternative to the method for determining whether the firstand second images are images of the same scene of steps 106 a-106 eillustrated in FIG. 4 , the processor 6 uses the accelerometer 17 tomeasure any movements of the mobile electronic device 2 (and thereforealso the camera 10) between a time of capture of the first image 60 anda time of capture of the second image 62 and the processor 6 determinesthat the first and second images 60, 62 are images of the same scene ifthe size of any movements of the camera 10 comply with one or morepredetermined movement criteria. For example, the processor 6 determinesthat the first and second images 60, 62 are images of the same scene ifthe size of any movements of the camera 10 are less than one or morecorresponding predetermined threshold values.

In a third alternative to the method for determining whether the firstand second images are images of the same scene of steps 106 a-106 eillustrated in FIG. 4 , the processor 6 determines a location andorientation of the mobile electronic device 2 (and therefore also thecamera 10) at the time of capture of each of the first and second images60, 62 from one or more signals received wirelessly by the antenna 18from one or more cellular base stations and/or from one or moresatellites such as one or more GPS satellites. The processor 6 thendetermines that the first and second images 60, 62 are images of thesame scene if the determined locations of the camera 10 at the times ofcapture of the first and second images 60, 62 comply with apredetermined location criteria and the determined orientations of thecamera 10 at the times of capture of the first and second images 60, 62comply with a corresponding predetermined orientation criteria. Forexample, the processor 6 determines that the first and second images 60,62 are images of the same scene if a difference between the determinedlocations of the camera 10 at the times of capture of the first andsecond images 60, 62 is less than a corresponding predetermined locationthreshold value and a difference between the determined orientations ofthe camera 10 at the times of capture of the first and second images 60,62 is less than a corresponding predetermined orientation thresholdvalue.

A fourth alternative to the method for determining whether the first andsecond images are images of the same scene of steps 106 a-106 eillustrated in FIG. 4 , is now described with reference to FIG. 7 . Inthe fourth alternative method for determining whether the first andsecond images are images of the same scene, the processor 6 identifiesat step 306 a an object 64 in the first image 60 and identifies the sameobject 64 in the second image 62. For example, the processor 6 may usean image processing algorithm to identify the object 64 in the firstimage 60 and to identify the same object 64 in the second image 62. Theimage processing algorithm may, for example, be based on a machinelearning algorithm. At step 306 b, the processor 6 determines, for eachof one or more properties of the object 64, a first value for theproperty of the object 64 from the first image 60 and a second value forthe property of the object 64 from the second image 62. The one or moreproperties of the object may, for example, include one or more of a sizeof the object 64, an aspect ratio of the object 64, a position of theobject 64, and an orientation of the object 64.

The processor 6 then determines at step 306 c whether, for each of theone or more properties of the object 64, the determined first and secondvalues of the property of the object 64 comply with a correspondingpredetermined criterion. For example, the processor 6 determines, foreach of the one or more properties of the object 64, a differencebetween the determined first and second values of the property of theobject 64, and the processor 6 determines whether, for each of the oneor more properties of the object 64, the determined difference betweenthe determined first and second values of the property of the object 64is less than a corresponding predetermined threshold value. If at step306 c, the processor 6 determines that the determined first and secondvalues of the property of the object 64 comply with the correspondingpredetermined criterion for each of the one or more properties of theobject 64, the processor 6 determines that the first and second images60, 62 are images of the same scene at step 306 d. If at step 306 c, theprocessor 6 determines for each of the one or more properties of theobject 64, that the determined first and second values for the propertyof the object 64 do not comply with the corresponding predeterminedcriterion, the processor 6 determines that the first and second images60, 62 are images of different scenes at step 306 e.

Various modifications are possible to the apparatus and methodsdescribed above with departing from the scope defined by the appendedclaims. For example, in an alternative method to any of the methodsdescribed with reference to FIGS. 2-7 for automatically testing theoperational status of the camera flash 12 of the mobile electronicdevice 2, the mobile electronic device 2 may enable the camera flash 12and prompt a user of the mobile electronic device 2 to use the camera 10to capture a first image of a scene. This alternative method maycontinue with the mobile electronic device 2 disabling the camera flash12 and prompting the user to use the camera 10 to capture a second imageof the same scene. It is an advantage of this alternative method thatany technical limitations preventing normal operation of the cameraflash 12 may be detected before capturing any images. Such technicallimitations may include low charge of a battery of the mobile electronicdevice 2 or any restrictions set on the use of the camera flash 12 bythe diagnostics application 19, for example.

Rather than the processor 6 of the mobile electronic device 2 executingdiagnostics application 19 thereby causing the mobile electronic device2 to perform the method for automatically testing the operational statusof the camera flash 12 of the mobile electronic device 2 as describedwith reference to FIGS. 2-7 , the processor 26 of the server 22 mayexecute the diagnostics application 30 thereby causing the server 22 tocommunicate with the mobile electronic device 2 via the communicationinterfaces 7, 27 and the cloud 50 to cause the mobile electronic device2 to perform the method for automatically testing the operational statusof the camera flash 12 of the mobile electronic device 2 as describedwith reference to FIGS. 2-7 .

The one or more camera settings may comprise an aperture setting, anf-stop, or an f-number.

The method may comprise reading the light source settings, the one ormore camera settings, and the one or more image properties for the firstand second images from the camera.

The method may comprise comprising reading the first and second imagesfrom the camera.

The method may comprise determining the image properties of the firstand second images from the image data of the first and second images.

The method may comprise selecting each predetermined camera settingcriterion and each predetermined image property criterion based at leastin part on the corresponding camera setting value and/or thecorresponding image property value when the camera captures the firstimage. This may be advantageous where the first image captures a scenewhich is relatively bright.

The mobile electronic device may comprise a mobile phone, a smart phone,a cell phone, or a tablet.

The camera and the light source may be fixed or attached in a fixedspatial relationship to an object or a device other than a mobileelectronic device.

The camera and the light source may form part of, or be defined by, orbe fixed or attached to, a security system for a building, a fixedstructure, or an enclosed area or space.

The camera and the light source may form part of, or be defined by, orbe fixed or attached to, a vehicle.

The light source may comprise, or be defined by, a light source providedwith a vehicle such as a head light or a tail light of a vehicle.

One of ordinary skill in the art will understand that one or more of thefeatures of the embodiments of the present disclosure described abovewith reference to the drawings may produce effects or provide advantageswhen used in isolation from one or more of the other features of theembodiments of the present disclosure and that different combinations ofthe features are possible other than the specific combinations of thefeatures of the embodiments of the present disclosure described above.

1. A method for use in testing an operational status of a light sourcefor illuminating a scene, the light source having a fixed spatialrelationship relative to a camera, and the method comprising: using thecamera to capture a first image when the light source is disabled; usingthe camera to capture a second image when the light source is enabled;and determining a test result indicating the operational status of thelight source based at least in part on: a light source setting when thecamera captures each of the first and second images, the light sourcesetting indicating whether the light source is disabled or enabled whenthe camera captures the first and second images; at least one of: one ormore camera settings when the camera captures the first and secondimages; and one or more image properties of the first and second images;and determining whether the first and second images are images of thesame scene.
 2. The method of claim 1, wherein the one or more camerasettings comprises at least one of: an ISO setting of an image sensor ofthe camera, an exposure index of an image sensor of the camera, asensitivity setting of an image sensor of the camera, or a gain settingof an image sensor of the camera; a shutter speed or an exposure time ofthe camera; and an aperture setting, an f-stop, or an f-number of thecamera.
 3. The method of claim 1, wherein the one or more imageproperties comprise at least one of: an image brightness parameterrepresentative of an average brightness of an image or an averageintensity of an image, or representative of an average brightness or anaverage intensity of a pre-defined portion or a pre-defined area of animage; and an image file size.
 4. The method of claim 1, comprisingreading the first and second images from the camera.
 5. The method ofclaim 1, comprising extracting from metadata associated or stored witheach of the first and second images, the light source settings, the oneor more camera settings, and the one or more image properties for eachof the first and second images.
 6. (canceled)
 7. The method of claim 1,comprising: determining, for each of the one or more camera settings,whether a camera setting difference between a camera setting valueassociated with the first image and a camera setting value associatedwith the second image complies with a corresponding predetermined camerasetting criterion; and determining, for each of the one or more imageproperties; whether an image property difference between an imageproperty value associated with the first image and an image propertyvalue associated with the second image complies with a correspondingpredetermined image property criterion.
 8. The method of claim 7;comprising selecting each predetermined camera setting criterion andeach predetermined image property criterion based at least in part onthe corresponding camera setting value and/or the corresponding imageproperty value when the camera captures the first image.
 9. The methodof claim 7, comprising determining a positive test result indicatingthat the light source is operational, or that the light source operatescorrectly or in compliance with a predetermined performancespecification if: the first and second images are determined to beimages of the same scene; one or more of the camera setting differencescomply with the corresponding predetermined criterion; and one or moreof the image property differences comply with the correspondingpredetermined criterion.
 10. The method of claim 7, comprisingdetermining a negative test result indicating that the light source isnon-operational, or that the light source is faulty or fails to complywith a predetermined performance specification if: the first and secondimages are determined to be images of the same scene; and at least oneof: one or more of the camera setting differences fails to comply withthe corresponding predetermined criterion; and one or more of the imageproperty differences fails to comply with the correspondingpredetermined criterion.
 11. The method of claim 1, comprisingdetermining a positive test result indicating that the light source isoperational, or that the light source operates correctly or incompliance with a predetermined performance specification if: the firstand second images are determined to be images of the same scene; thesecond image has a localised feature or artefact of a greater brightnessthan one or more adjacent areas or regions of the second image; and thefirst image has no localised feature or artefact of a greater brightnessthan one or more adjacent areas or regions of the first image, whichlocalised feature or artefact of the first image is located at aposition in the first image that corresponds to a position of thelocalised feature or artefact in the second image.
 12. The method ofclaim 11, comprising determining a negative test result indicating thatthe light source is non-operational, or that the light source is faultyor fails to comply with a predetermined performance specification if: itis determined that the first and second images are images of the samescene; the second image has a localised feature or artefact of a greaterbrightness than one or more adjacent areas or regions of the secondimage; and the first image has a localised feature or artefact of agreater brightness than one or more adjacent areas or regions of thefirst image, which localised feature or artefact of the first image islocated at a position in the first image that corresponds to a positionof the localised feature or artefact in the second image.
 13. The methodof claim 11, comprising using an image processing algorithm such as amachine learning algorithm to identify any localised feature or artefactof a greater brightness than one or more adjacent areas or regions ofthe first and/or second images.
 14. The method of any one of claim 1,comprising determining an inconclusive test result for the operationalstatus of the light source if it is determined that the first and secondimages are not images of the same scene.
 15. The method of claim 1,wherein determining whether the first and second images are images ofthe same scene comprises: identifying an object in the first image, forexample using an image processing algorithm such as a machine learningalgorithm; identifying the same object in the second image, for exampleusing an image processing algorithm such as a machine learningalgorithm; determining, for each of one or more properties of theobject, a first value for the property, of the object from the firstimage and a second value for the property of the object from the secondimage; and determining that the first and second images are images ofthe same scene if, for each of the one or more properties of the object,the first and second values for the property of the object comply with acorresponding predetermined criterion.
 16. The method of claim 15,wherein the one or more properties of the object comprise one or moreof: a size of the object, an aspect ratio of the object, a position ofthe object and an orientation of the object.
 17. The method of claim 1,wherein determining whether the first and second images are images ofthe same scene comprises: determining a quantitative degree ofsimilarity such as a cross-correlation between the first and secondimages; and determining that the first and second images are images ofthe same scene if the quantitative degree of similarity between thefirst and second images complies with a predetermined image similaritycriterion.
 18. The method of claim 1, wherein determining whether thefirst and second images are images of the same scene comprises:determining a distance from the camera to an object located at apredetermined position in the first image; determining a distance fromthe camera to an object located at a predetermined position in thesecond image, which predetermined position in the second imagecorresponds to the predetermined position in the first image; anddetermining that the first and second images are images of the samescene if the determined distance from the camera to the object at thepredetermined position in the first image and the determined distancefrom the camera to the object at the predetermined position in thesecond image comply with a predetermined distance criterion.
 19. Themethod of claim 18, wherein determining whether the first and secondimages are images of the same scene comprises: measuring a distance fromthe camera to the object at the time of capture of the first image; andmeasuring a distance from the camera to the object at the time ofcapture of the second image.
 20. The method of claim 19, whereinmeasuring the distance from the camera to the object at the time ofcapture of each of the first and second images comprises: transmittingmodulated electromagnetic radiation such as modulated light from anemitter to the object and receiving modulated electromagnetic radiationreflected from the object at a detector; and determining a delay betweenemitting the modulated electromagnetic radiation from the emitter anddetecting the reflected modulated electromagnetic radiation at thereceiver, wherein the emitter and the detector have a fixed spatialrelationship with respect to each other.
 21. The method of claim 1,wherein determining whether the first and second images are images ofthe same scene comprises: measuring any movements of the camera betweena time of capture of the first image and a time of capture of the secondimage; and determining that the first and second images are images ofthe same scene if the size of any movements of the camera comply withone or more predetermined movement criteria.
 22. The method of claim 1,wherein determining whether the first and second images are images ofthe same scene comprises: determining a location and orientation of thecamera at the time of capture of each of the first and second images;and determining that the first and second images are images of the samescene if the determined locations of the camera at the times of captureof the first and second images comply, with a predetermined locationcriterion and the determined orientations of the camera at the times ofcapture of the first and second images comply with a correspondingpredetermined orientation criterion.
 23. The method of claim 1, whereinthe light source comprises a camera flash provided with, housed with, orfixed or attached to, the camera.
 24. The method of claim 1, wherein thecamera and the light source form part of, are defined by, or are fixedor attached to, a computing device such as a mobile phone, a smartphone, a cell phone, a tablet, a desktop computer, a laptop computer, aworkstation or an Internet-of-Things (IoT) device.
 25. An applicationfor a mobile electronic device comprising a camera and a light source,or an application for a server configured for communication with amobile electronic device which mobile electronic device comprises acamera and a light source, wherein, when executed by a processor of themobile electronic device or a processor of the server, the applicationcauses the mobile electronic device to perform the method as claimed inclaim 1.